Summary: Mark 13, Matthew 24 and Luke 21 are all dedicated to the prophetic warning given by the Lord Jesus to His disciples as what to expect as it pertains to the spread of the Gospel and the increasing evil of the world.
Apostate Judaism has had its last chance. Jesus had finished with the Pharisees, Sadducees, and others who had challenged His authority, teachings, and miracles. He will again face them on the day of His crucifixion. He had shed tears over Jerusalem and had pronounced judgment upon it. The apostles are fixated not on these events but upon the symbol of their faith, the ornate and beautiful Temple that sat in the center of the city. While it was a wonder of the ancient world and a sight to behold, it was now nothing more than a whitewashed tomb that reeked with the stench of religiosity and spiritual corruption.
The apostles pointed out what is to them a symbol of spiritual greatness, but Jesus replied to their comments with stern criticism, telling them that the Temple would soon be destroyed. As they crossed the Kidron Valley and headed to the Mount of Olives, the apostles asked Him when this would happen and what would be the signs to expect. Jesus then presented His longest and most detailed teaching on what will happen to the world as the days draw nearer to the end of life as they knew it.
Jesus started by warning them that false Messiahs and Deliverers would appear throughout history to deceive and lead people away from the truth of the Gospel. From the origins of Romanism to the rise of the cults that have burst upon the scenes in the past centuries (Jehovah's Witnesses, Mormonism, Christian Science, Seventh-Day Adventists, the Worldwide Church of God (Herbert W. Armstrong) along with progressive and leftist theology and biblical interpretations, the rise of Islam, Buddhism, Hinduism, and the New Age movement and the growth and acceptance of devil worship worldwide all show that false religions would arise as the days drew nearer to the return of the Lord.
Wars and conflicts will increase and be more common as the days approach to Jesus' return. Right now the world is experiencing increased chaos in nations, civil wars, riots, the rise of violence and the spirit of murder, with the last century being the bloodiest and most brutal in terms of war. There was World War I, World War II, Korea, Vietnam, the Gulf Wars, the wars in Iraq and Afghanistan, continual conflict between Israel and Iran and the proxy governing powers such as Hamas, Hezbollah, ISIS, and others that have continually kept the Middle East in a state of turmoil. There is not a single nation on Earth now that is not involved in some type of conflict, and it will worsen.
There will be an increase in natural disasters such as constant and growing numbers of earthquakes in places not known for such activity. Hurricanes and tornadoes are occurring in places such as the UK, China, Russia, and parts of Europe that had never had these types of weather extremes. There are increases in floods, landslides, droughts, and intense heat in places where nothing like it has ever happened, such as 100 degree temperatures in western Canada and the Pacific Northwest (Washington, Oregon). The dark culprit seems to always be "Climate change", primarily caused by humanity, green hose gases, and occasional gas from the backend of farm animals according to some politicians. The book of Revelation shows us that we are only witnessing the start of what the LORD will do to unregenerate humanity as He brings judgments upon this wicked and rebellious world.
Because of natural disasters and our insistence on rewiring the genetic makeup of plants and animals, we are now having to deal with the reality of food shortages and famines. We have witnessed the backlog of goods that needed to be sent to stores and other retailers but were kept from doing so because of the COVID-19 situation, where whole nations came to a standstill. Many states and countries faced empty shelves in grocery stores and shortages of necessities that were in stock a short time ago. This country has not had to deal with the idea of a famine as other countries have, but we will find ourselves in just such a situation sooner than we think. There are calls from food supply companies to purchase their product and be prepared for hard times to come, and it will not get better once that reality hits us.
As the end times get closer, Jesus warned His apostles and all who would follow Him in the times to come that they will be hated ,slandered, mocked, hunted down, blamed for the world's troubles, boycotted, and killed for their faith in Him. The twentieth century alone saw more people being killed for their faith In Christ than at any other time in history, and even now the persecution is getting worse around the world and here in America. Churches are being burned down in Canada and the government does nothing to stop it. More fanatics are entering places of worship here and killing everyone inside. The Columbine shootings of the 1990's saw teenagers who died confessing Christ as the demonically driven gunmen mowed them down. ISIS terrorists produced videos of Christians in Egypt, Iraq, and Syria being decapitated, sold into slavery, their babies being crucified and children raped and tortured in order for them to recant their faith in Christ as the rest of the world basically stood by and did nothing. The anti-God forces are growing rapidly and right now less than 50% of Americans even consider themselves religious as atheism permeates our schools and colleges and the whole of society. Those believers who are praying for a national revival may be doing so in vain.